1. Field of the Invention
The present invention relates to word processing systems having interactive display terminals, and more particularly to such systems with terminals having "character box" displays, i.e., displays which form the alphanumeric characters through the generation of such characters in "character boxes" on the display.
2. Description of Prior Art
Word or text processing systems having interactive display terminals permitting an operator to extensively edit and format alphanumeric data which is, in turn, printed out on an associated printer have been in ever increasing demand in the office products and systems field. Since a great many letters, articles to be published and books require some graphic material to be formatted into documents along with the alphanumeric text, there has been a need for improved editing capability with respect to graphics on word processor displays as well as improved expedients for producing documents which contain graphics in addition to alphanumeric data. Improving capability of word processing systems to handle graphics has presented a problem. The best quality graphics is conventionally produced through plotters with styli which can access or address any point on the document and proceed in a vector to any other point on the document. However, conventional word processing systems with interactive display terminals generally operate the display terminal as a character generation or "character box" display. In such a display, an encoded representation of each of a font of characters is stored in a character generator memory, and as each character is to appear on the display during each display refresh cycle, the character generator memory is addressed and the coded representation of that particular character is taken from the memory and displayed in a particular and designated "character box" on the display. However, the form of display most compatible with graphics to be formed on documents by vector means such as plotters would be an All Point Addressable (APA) display. On such displays, the screen is divided into an X,Y matrix of points, each of which may be addressed and turned on in order to create the image. Thus, during the present work on adapting vector graphics producing apparatus such as plotters to word or text processing systems, we are faced with the problem of finding a compatible method of displaying graphic data for editing purposes together with the alphanumeric data conventionally displayed and edited in word processing systems.
The following prior art is representative of the handling of graphics on various displays.
U.S. Pat. No. 4,246,578, I. Kawasaki et al, Pattern Generation Display System, issued Jan. 20, 1981. This patent discloses a display on which both graphics and alphanumeric data may be shown. It does not use a character generator for the alphanumerics. Rather, all displayed material is generated through some sort of an All Points Addressable system.
U.S. Pat. No. 4,272,767, R. H. Lacy, Display System for Displaying Information in the Form of a Horizontally Oriented Curve on a Raster-Type CRT, issued June 9, 1981. In this display terminal for showing both alphanumeric and graphic material, the alphanumerics are generated through character generation but the graphics or curves appear to be generated by some other means involving vectors.
U.S. Pat. No. 4,338,599, S. Leininger, Apparatus for Alpha-Numeric/Graphic Display, issued July 6, 1982 covers a display for graphic and alphanumeric information. While the alphanumeric information appears to be displayed through some sort of character generation, the graphic data is displayed through a different scheme which does not appear to utilize character generation.
U.S. Pat. No. 4,283,723, R. H. Bickley et al, Apparatus and Method for Providing Digital and/or Bar Graph Displays of Measured Quantities, issued Aug. 11, 1981 appears to relate to a very specialized display forming both characters and simple bar graphs through a character generation method. However, the teaching is quite specialized and appears to be in no way suggestive of or related to the production of printed documents and particularly a word processing system controlling the printing of documents on the formation of graphics on such documents.